The present invention relates to an electrophotographic copier, facsimile apparatus, printer or similar office equipment having a power supply and, more particularly, to a device installed in such office equipment for setting operation modes immediately after the power supply has been turned on.
Today, offices are equipped with various kinds of machines such as a copier, a facsimile apparatus and a printer to enhance efficient business transactions. An electrophotographic copier, for example, adapted to transfer an image developed by toner to a paper sheet is provided with a cover or door at its front end to facilitate the removal of a jamming sheet and maintenance. When the front cover is opened, major parts and elements of mechanical sections of the copier are uncovered. Since mechanically operated sections and sections powered by high voltages are disposed inside of the cover, an interlock switch interlocked with the opening and closing motions of the door is provided to eliminate hazards ascribable to those sections. The power supply of the copier is automatically shut off when the door is opened.
The electrophotographic copier or similar office machine has various functions and is provided with an operation board which is accessible for selectively using the functions, i.e., for entering commands to set up desired operation modes. Upon turn-on of the power supply, the machine is automatically initialized to set up the commonest operation modes. The operator of the machine may manipulate the operation board to replace the commonest modes with any other desired modes after turning on the power supply. When the cover is opened to make access to the interior of the copier for replacing a developing cartridge, checking a total copy counter or a paper transport path or similar purpose, the power supply is shut off by the interlock switch. When the cover is closed after the replacement or the check, the operation mode is initialized. More specifically, when the cover is opened, the power supply of the copier having been operated in modes other than the initial or commonest modes is turned off and, when the door is closed again, the operation modes are returned to the commonest ones. To restore the copier to the previous modes, the operator has to manipulate the operation board all over again. Nevertheless, shutting off the power supply when the cover is opened and initializing the operation modes upon the turn-on of the power supply are essential.
There has been proposed an implementation for inhibiting the operation modes from being initialized when the power supply is turned off when toner runs out or when a paper sheet jams the transport path. Such a prior art scheme, however, fails to preserve the particular operation modes except for those special occurrences, i.e., the operation modes have to be set again in the event of maintenance or similar ordinary work. In a copier with a programming function which is implemented by a memory, the initialization of the operation modes is prevented by backing up the memory constantly or by backing it up by an exclusive spare power supply only when a paper jam or similar trouble occurs and when the front door is open. A drawback with the constant back-up scheme is that when a power switch of the machine is turned on for the first time in the morning, an operation mode selected the day before appears as they are to puzzle the operator. On the other hand, the selective back-up scheme is disadvantageous in that an extra power supply for backing up is needed and in that extra and complicated means for sensing a paper jam and an open position of the door are indispensable. A non-volatile memory may be used to allow a person to register operation modes selected and, after the shut-off the power supply, to call them out of the memory by manipulating keys on the operation board. However, the manipulations for registering and calling the operation modes are complicated and therefore awkward.